Cisco Catalyst 9800 Series Wireless Controller Software Configuration Guide, Cisco IOS XE 26.1.x

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Cisco Catalyst 9800 Series Wireless Controller Software Configuration Guide, Cisco IOS XE 26.1.x

Mesh background scanning

Updated: April 10, 2026

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Describes background channel scanning and MAP fast ancestor find mode for rapid failover, including configuration and verification procedures through both GUI and CLI.

A mesh background scan is a mesh networking feature that

  • enables mesh access points (MAPs) to find and connect to better potential parents across channels

  • maintains stable uplinks by proactively scanning for available parent nodes, and

  • reduces reconnection delay after parent loss by using a neighbor list instead of scanning all channels.

When background scanning is disabled, a MAP has to scan all the channels of the regulatory domain after detecting a parent loss in order to find a new parent and go through the authentication process. This delays the time taken for the mesh AP to connect back to the controller.

When background scanning is enabled, a MAP can avoid scanning across the channels to find a parent after detecting a parent loss, and select a parent from the neighbor list and establish the Adaptive Wireless Path Protocol (AWPP) link.

Background scanning and MAP fast ancestor find mode

Background scanning and MAP fast ancestor finding are features that

  • optimize MAP connectivity and parent selection in Cisco mesh wireless networks

  • minimize mesh tree convergence time when MAPs lose connectivity with their parents, and

  • reduce the need for beacon transmission during network formation.

Background scanning and MAP fast ancestor finding details

Cisco mesh access points (MAPs) perform the following functions:

  • Interconnects over wireless links in a tree topology,

  • Uses Adaptive Wireless Path Protocol (AWPP) to create and maintain their topology, and

  • Supports additional features: Background Scanning and MAP Fast Ancestor Finding.

When a MAP comes up, it tries to look for another MAP (parent) to join and reach the gateway through a RAP. The same happens when a MAP loses connectivity with its existing parent. This procedure is known as mesh tree convergence.

The Background scanning feature:

  • Updates MAPs about neighboring channels and helps find new parents swiftly by scanning all available channels.

  • Minimizes the time spent during scan-and-seek phases when a MAP loses its current parent.

  • Does not speed up the authentication process to the new parent.

A child MAP maintains its uplink with its parent by using the AWPP adjacency request/response messages, which act as keepalive signals. If consecutive response messages are lost, the parent is considered lost, and the child MAP searches for a new parent. A MAP maintains a list of neighbors ON the current ON channel. If the AP loses its current parent, it roams to the next best potential neighbor. If no other neighbors are found, the AP scans or seeks across all the channels or subset channels to find a parent. This process is time-consuming.

The MAP Fast Ancestor Finding feature enables a method to reduce the need for sending or receiving beacons during network formation, while starting or deploying a new mesh network.

Configure background scanning (GUI)

Enable background scanning on a wireless mesh profile to improve network performance and reliability.

Procedure

1.

Choose Configuration > Wireless > Mesh > Profiles.
2.

Select your desired profile.
3.

In General tab, check the Background Scanning check box.

4.

Click Update & Apply to Device.

You have activated background scanning for the selected wireless mesh profile.

Configure background scanning

To enable background scanning in mesh deployments so that mesh access points (MAPs) can detect neighboring channels and identify better parent nodes, maintaining optimal uplink connections.

Procedure

1.

Enter global configuration mode.

Example:

Device# configure terminal
2.

Configure a mesh profile and enter the mesh profile configuration mode.

Example:

Device(config)# wireless profile mesh mesh-profile-name
3.

Configure background scanning to enable mesh access points to find better parent nodes and maintain optimal connections.

Example:

Device(config-wireless-mesh-profile)# background-scanning

Background scanning is enabled in the mesh profile. Mesh APs scan neighboring channels to find better parent nodes. This helps maintain optimal uplink performance in the mesh network.

Device# configure terminal
Device(config)# wireless profile mesh mesh-profile-name
Device(config-wireless-mesh-profile)# background-scanning

Configure AP fast ancestor find mode (GUI)

Enable a child MAP to synchronize with any neighbor parent MAP across all channels.

Use the GUI to configure the MAP Fast Ancestor Find feature within a mesh profile.

Follow these steps to configure AP fast ancestor find mode through the GUI:

Procedure

1.

Choose Configuration > Wireless > Mesh > Profiles.
2.

Click Add.

The Add Mesh Profile page is displayed.
3.

In the Add Mesh Profile page, click the General tab.
4.

In the Name field, enter the mesh profile name.
5.

In the Description field, enter a description for the mesh profile.
6.

Check the MAP Fast Ancestor Find check box to enable a MAP (child) to synchronize with any neighbor MAP (parent) across all channels.
7.

Click Apply to Device to save the configuration.

The MAP Fast Ancestor Find feature is enabled for the specified mesh profile.

Configure background scanning and MAP fast ancestor find mode (Task)

Configure background scanning and MAP fast ancestor find mode using the CLI within a mesh profile for detailed configuration options.

Follow these steps to configure background scanning and MAP fast ancestor find mode through the CLI:

Procedure

1.

Enter global configuration mode.

Example:

Device# configure terminal
2.

Configure a mesh profile and enter mesh profile configuration mode.

Example:

Device# wireless profile mesh default-mesh-profile
3.

Enable background scanning in mesh deployments.

Example:

Device(config-wireless-mesh-profile)# background-scanning
Note

In Cisco Catalyst 9124 Series Access Points, a dedicated RF ASIC radio is used for background scanning.
4.

Enable fast ancestor find mode.

Example:

Device(config-wireless-mesh-profile)# map-fast-ancestor-find
Background scanning and MAP fast ancestor find mode are enabled for the specified mesh profile.

Example

Device# configure terminal
Device# wireless profile mesh default-mesh-profile
Device(config-wireless-mesh-profile)# background-scanning
Device(config-wireless-mesh-profile)# map-fast-ancestor-find

Verify background scanning and MAP fast ancestor find

To verify whether the Background Scanning and MAP Fast Ancestor Find features are enabled, run the show wireless profile mesh detailed command.

To verify the background scan, use this command:

Device# show wireless profile mesh detailed Mesh_Profile | i Background Scan
Background Scan               : ENABLED

To verify MAP Fast Ancestor Find, use this command:

Device# show wireless profile mesh detailed Mesh_Profile | i MAP fast ancestor find
MAP fast ancestor find        : ENABLED